drag_and_drop.md

keywords	title	description	contributors
Adobe Express Express Add-on SDK Express Editor Adobe Express Add-on SDK SDK JavaScript Extend Extensibility API Drag and Drop	Use Drag-and-Drop	Use Drag-and-Drop.	https://github.com/undavide https://github.com/hollyschinsky

Use Drag-and-Drop

With local images

You must invoke the addOnUISdk.app.enableDragToDocument() method for each draggable image to implement this feature. It accepts two parameters: the HTMLElement and an object with a previewCallback() that returns the image URL for preview purposes, and a completionCallback() that fetches the corresponding blob to finalize insertion into the document.

You also need to listen for "dragstart" and "dragend" events to manage logs or other custom behaviour when the user interacts with the images.

Example

import addOnUISdk from "https://new.express.adobe.com/static/add-on-sdk/sdk.js";

// Wait for the SDK to be ready before rendering elements in the DOM.
addOnUISdk.ready.then(async () => {
  // Create the image element in the DOM.
  const image = document.createElement("img");
  image.id = "image.jpg";
  // The image is local to the add-on.
  image.src = "./images/image.jpg";
  image.addEventListener("click", addToDocument);

  // Enable drag to document for the image.
  addOnUISdk.app.enableDragToDocument(image, {
    previewCallback: (element) => {
      // return the new URL for preview purposes
      return new URL(element.src);
    },
    completionCallback: async (element) => {
      // return the blob for the image
      return [{ blob: await getBlob(element.src) }];
    },
  });

  // Add the image to the document.
  document.body.appendChild(image);
});

// Utility functions

//Add image to the document.
async function addToDocument(event) {
  const url = event.currentTarget.src;
  const blob = await getBlob(url);
  addOnUISdk.app.document.addImage(blob);
}

// Handle "dragstart" event
function startDrag(eventData) {
  console.log("The drag event has started for", eventData.element.id);
}

// Handle "dragend" event
function endDrag(eventData) {
  if (!eventData.dropCancelled) {
    console.log("The drag event has ended for", eventData.element.id);
  } else {
    console.log("The drag event was cancelled for", eventData.element.id);
  }
}

// Get the binary object for the image.
async function getBlob(url) {
  return await fetch(url).then((response) => response.blob());
}

With remote images or audio

To implement drag and drop with remotely hosted images, you similarly invoke addOnUISdk.app.enableDragToDocument(), but you fetch the resource from its remote URL. Provide a previewCallback() that returns the preview URL and a completionCallback() that retrieves the image as a blob. You can then attach the same "dragstart" and "dragend" event handlers to log or customize interactions as needed.

To drag audio content, you must specify an additional attributes object with a title property. A note on how to include it is found in the following example.

Example

import addOnUISdk from "https://new.express.adobe.com/static/add-on-sdk/sdk.js";

// Enable drag support for an element
function makeDraggableUsingUrl(elementId: string, previewUrl: string) {
  const image = document.getElementById(elementId);

  const dragCallbacks = {
    previewCallback: (image: HTMLElement) => {
      // Return a new URL for the remote preview
      return new URL(previewUrl);
    },
    completionCallback: async (image: HTMLElement) => {
      // Fetch and return the image blob
      const imageBlob = await fetch(image.src).then((response) =>
        response.blob()
      );
      return [{ blob: imageBlob }];

      // ⚠️ for audio content, an attributes object
      // with the title is mandatory. For example:
      // return [{ blob: audioBlob, attributes: { title: "Jazzy beats" } }];
    },
  };

  try {
    addOnUISdk.app.enableDragToDocument(image, dragCallbacks);
  } catch (error) {
    console.log("Failed to enable DragToDocument:", error);
  }
}

// Log start of the drag event
addOnUISdk.app.on("dragstart", (eventData: DragStartEventData) => {
  console.log("The drag event has started for", eventData.element);
});

// Log end of the drag event
addOnUISdk.app.on("dragend", (eventData: DragEndEventData) => {
  if (!eventData.dropCancelled) {
    console.log("The drag event has ended for", eventData.element);
    disableDragToDocument();
  } else {
    console.log("The drag event was cancelled for", eventData.element);
    console.log("Cancel Reason:", eventData.dropCancelReason);
  }
});

Notes

If the content being dragged is an animated GIF, it will be added as an animated GIF to the document, as long as it fits the size criteria for animated GIF's. In the event that it doesn't fit the size criteria, an error toast will be shown to the user.

Since the Add-on SDK uses pointer event handlers to perform drag operations, you should ensure that you don't attach any pointer event handlers that prevent default or stop propagation. Adding those types of handlers will kill the built-in handlers and cause the events not to work.

You should not attach click event listeners to drag-enabled elements in the capture phase, as the Add-on SDK attaches a cancelClickEvent handler to drag-enabled elements to ensure that the automatic click (pointer down + pointer up automatically fires a click event) doesn't fire. Adding other handlers to this same element will trigger them on drag & drop completion.

Use Chrome devTools to check the handlers attached to the element and its ancestors to identify any that may be causing conflicts with drag and drop handlers.

There are several code samples that implement drag and drop, including the import-images-using-oauth and pix projects that you can reference.